20. A neutral atom contains A. more protons than electrons. B. more electrons th
ID: 271745 • Letter: 2
Question
20. A neutral atom contains A. more protons than electrons. B. more electrons than protons e same number of electrons and protons D. only neutrons. E. None of these choices is correct 21. The integumentary system has many functions, one of which is A. protection from cancer. B. production of Vitamin E C. detection of painful stimuli D. regulation of acid-base balance. E. prevention of albinism. 22. The foramen magnum is a large opening in the base of the skull for the A. optic nerve. B. carotid arteries. C. internal jugular veins. D. facial and vestibulocochlear nerves. E. spinal cord. 23·The study of the structural features and functions of the cell is A. cytology B. histology C. molecular biology. D. microbiology E. surface anatomy. 24. A blood clot stimulating even more blood clotting is an example of A. negative feedback B. positive feedback. C. neutral feedback. D. metabolism. E. There is no feedback involved.Explanation / Answer
20. C
Neutral atom means it has no charge (neither positive nor negative charge). Atom consists of some number of positively charged protons, some number of negatively charged neutron, some neutrons having no charge. Now, if the number of proton is higher than the electron, then the atom becomes more positive, hence positively charged. If the number of electron becomes higher than the proton, then the atom becomes more negative, negatively charge. As one proton and one electron carry same amount of charges, so when the atom is neutral means it has no charge, then the number of electron and proton must be equal. So that, the net charge of each other's is neutralised.
21. C
Integumentary system comprises of skin , hair, nail, glands (exocrine) etc. The important functions of this integumentary system are - protection, sensation & regulation.
It protects our internal structure from the environmental hazards. Now, skin and other parts can also respond when a painful stimulus is applied on body. It regulates salt- water balance, body temp.
22. E
Foramen of magnum is a large hole present on the occipital bone of the skull. It has a large anterior- posterior diameter of about 3.5 cm and width of 3 cm. It is the largest foramen of the skull.
Spinal cord which is extended from the medulla of brain runs through this large oval hole and exits the skull or the cranial cavity.
23. A.
Etymology - Cyto - cell, logy - logia- study.
It is the study of cells where the structure, function , chemical aspects of different cell types (from animal and plant both) are discussed. It studies the cell the basic fundamental structual amd functional unit of life. It began with the experiment of Robert Hooke with cork.
24. B
Feedback mechanism is a type of function where the end result of a reaction goes to the starting point of that reaction to either stimulate (positive feedback) or depress the reaction (negative feedback). This occurs in a repetitive loop.
When a blood clot stimulates more clotting , it means the positive feedback mechanism.
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